Closure cap



United States Patent 3,152,711 CLGSURE CAP George V. Mumford and NormanC. 'Geithman, Toledo, Ohio, assignors to GWens-llllinois Glass Company,a corporation of Ghio Filed Nov. 14, 1960, Ser. No. 68,859 Claims. (Cl.2l5--38) This invention relates to closure caps, and more particularlyto sheet metal closure caps for hermetically sealing containers such asjars and bottles which are adapted for the preservation of comestibles.

In the preserving of comestibles it is common practice to place themWhile in a heated condition in a glass container and to provide ahead-space into which steam or an inert gas is introduced. This steam orgas replaces any air that may be present in the head-space of thecontainer. Immediately thereafter the container is closed with agasket-containing cap. If a tight seal is initially obtained between thecap and container it is known that as the hot food and the receptacleare cooled the entrapped steam condenses and an etlective vacuum iscreated in the container. The purpose of the gasket is to provide andmaintain a hermetic seal in order that the food is preserved duringstorage.

Due to various uncontrollable factors, it is not always possible tomaintain an air-tight seal with the result that over a period of timeair which contains various bacteria, molds, etc. may seep into thecontainer and contaminate the food with the result that the consumer maysufier ill effects from consuming such food. The problem then arises asto how this failure of the closure cap to provide an air-tight seal mayreadily be determined prior to the time at which the container isopened. It often is not possible for a consumer to determine merely bylooking at the container or the food therein that the same has or hasnot been contaminated unless the contamination has progressed to such anextent that it is clearly visible on the food. In the prior art, variousclosure caps have been proposed for sealing containers. For instance, inU.S. Patent No. 2,458,360 to Pay et al., they propose the provision of aclosure device having a curvilinear top portion which allegedly assumesa concave position if sufiicient vacuum is present in the container anda convex position when insufficient vacuum is present. This change inposition is also allegedly accompanied by an audible click.

This method has not proved satisfactory because the change from theconcave to the convex configuration will take place slowly upon thegradual reduction of the vacuum thereby making it very diflicult, if notimpossible, to determine by visual means the absence or presence of thedesired vacuum in the container. In addition, the curvilinear topportion renders it almost impossible to stack a container having such aclosure cap on top of another container containing a like cap. Also,when the cap is removed the audible click, if present at all, is veryfaint so that if the consumer has been educated to expect a loud clickupon the opening of the container, then upon hearing such a barelyaudible click, he will naturally assume that the vacuum was not presentin the container and that the food may be spoiled. If such occurs, theconsumer will be reluctant to use thecontents of the container and maybe led to doubt the skill of the manufacturer of the foods, therebydamaging its sales.

It is, therefore, an important object of the present invention toovercome the above described difficulties of the prior art. i

It is a further object of the present invention to provide a sheet metalclosure cap which has a panel configuration that assumes a concaveposition in the presence of a vacuum in the container and rapidlyassumes. aconvex 3,152,7ll Patented Get. 13, 1964 position when thedesired vacuum is released and is accompanied by a loud click.

It is a further object of the present invention to provide a sheet metalclosure cap whose panel configuration is such that the presence orabsence of the desired vacuum in the container may be readily determinedby touch or sight.

Another object of the present invention is to provide a sheet metalclosure cap for hermetically vacuum sealing a container in which thepresence or absence of vacuum in the container may readily be determinedby mechanical or photo-electrical devices which react to changes in thepanel contour of the caps in response to conditions internally of thesealed container.

A further object of the present invention is to provide a sheet metalclosure cap of simple construction, which, when used to hermeticallyvacuum seal a container, will provide a loud audible click when the sealis broken.

The present invention contemplates a closure cap formed from sheet metalhaving certain specific characteristics, for hermetically vacuum sealinga glass container. This cap comprises a disc-like panel portion, adepending attaching skirt at the periphery of the panel portion and asealing gasket carried by the cap. The panel portion has an annularsubstantially flat area in proximity to its periphery and a normallyupwardly domed central part peripherally defined by the substantiallyflat area. When this cap is placed on the glass container and the lattervacuumized, the major portion of the upwardly domed central part assumesa concave configuration. This being in the center of the panel portionmakes its presence readily determinable by either sight, touch, or bymechanical devices, which is contrary to the prior art devices whosedomed portion consisted of the entire top panel.

If, for some reason, there is seepage of air into the container over aperiod of time, the vacuum therein will gradually be destroyed and whenthe vacuum reaches a certain point the cap panel will suddenly move fromits concave to its convex position. This movement is accompanied by avery sharp click, thereby audibly indicating the loss of vacuum. Moreimportantly, when the consumer breaks the vacuum seal by removing thecap, such will be accompanied by the same sharp and audible click,thereby indicating that the desired vacuum was present in the containerup to the point of its opening. It can readily be seen that such a capwhich permits very quick and easy determination of the presence orabsence of vacuum in the container will be very useful in the foodprocessing industry, particularly the baby food industry wherein thequick detection of probably spoiled food is most desirable.

The accomplishment of this invention and the foregoing objects will bereadily understood by reference to the following detailed descriptiontaken in conjunction with the accompanying drawing in which:

FIGURE 1 is a plan View showing the closure device embodying the presentinvention;

FTGURE 2 is a view partly in elevation and partly in section of theclosure cap taken along lines 2-2 of FIGURE 1, such cap being afiixed toa glass container; and

FIGURE 3 is an enlarged sectional view of the closure cap of FIGURE 2.

Referring now to the drawing which illustrates a preferred form of thisinvention, reference numeral 19 denotes a mouth-defining neck portion ofa glass jar 11 which is hermetically sealed by a sheet metal closure capC. The critical characteristics of this sheet metal will be explainedhereinafter. The closure cap C is provided with a conventional or anypreferred form of sealing ring or gasket 13 composed of an elastomericmaterial such I as arubber composition, plastisol or the like. Thecircular neck 10 of the jar 11 is formed with a relatively flat topsealing surface, or rim 14 and may also be provided with conventionalcorner and side sealing surfaces. Below the rim 14 and externally of theneck is a closure cap retaining projection 15, such being a continuousscrewthread or one of a series of lugs. It may also be formed as aconventional single annular rib over which the cap skirt is forced. Thefinish of the glass jar 11 is or may well be conventional and requiresno further discussion or illustration.

The sheet metal cap C comprises a flat circular top portion, or panel16, having an annular depending attaching skirt 17 at its peripherywhich when the cap is affixed to a container surrounds the neck 10 andis radially spaced therefrom. The panel portion 16 is provided with anannular substantially flat area 12 in proximity to its periphery beingin a plane normal to the cap axis and a normally upwardly domed centralpart 18 peripherally defined by the flat area 12.

The normally upwardly domed or convex central part 18 is axiallydeformable to a concave position as shown by the dotted lines in FIGURE3. The domed central part 18 is substantially parabolic in shape andthus does not exhibit in cross-section any straight or fiat portions.Preferably the domed central part 13 at its highest point has a radiusof about tolO inches and a radius at its periphery of about /2 to 1inch.

The periphery of the cap panel 16 may assume any desired configuration,such as the illustrated upwardly formed hollow rib 21 which provides aninternal gasket accommodating channel 22. This illustrated peripheralconfiguration is more fully explained in application Serial No. 62,950,filed Oct. 17, 1960, and now Patent Number 3,096,898, in the names ofJohn Hohl and Jack M. Wheaten, entitled Container and Closure CapTherefor, and owned by the common assignee.

The cap C may be secured to the glass container by any conventionalmeans, such as an internal bead, a screw thread, or as illustrated,peripherally spaced internal lugs 20 which are integrally formed on thelower portions of the attaching skirt 17 and lock with the aforementioned projections 15 on the container neck.

The upwardly domed central part 18 in the absence of a vacuum normalyassumes the convex configuration shown in full lines in FIGURE 3. Whenthe cap C is placed on a jar 11 and a suitable vacuum is provided in thehead-space between the product and the cap, the central part will assumethe concave configuration shown in dotted lines in FIGURE 3. The flatarea 12 also moves downwardly with the central part. However, such is soslight that it cannot be detected by the naked eye and it has not beenillustrated for purposes of clarity. The concave configuration isreadily detected by sight or feel and thus it is simple for one todetermine that a vacuum is present in the jar 11. This configurationalso makes it possible to electronically inspect the filled containersto determine the presence or 'absence of the required vacuum. In theprior art, the caps would scatter the light rays making it verydifiicult if not impossible to position the device so as to only rejectthe containers possessing less than the desired vacuum. The concaveconfiguration of the caps of this invention gathers the light rays intoa narrow bandthereby permitting accurate positioning of the device toinsure rejection of only the bad containers.

Upon release of the vacuum the domed concave central part 18 snaps toits convex or normal position and this is accompanied by a very loud andaudible click. Such a click will assure the consumer that a vacuum waspresent in the container thereby reassuring him that no contamination ispresent in the product.

It has been found that the above described results can be obtained onlyby the use of the aforementioned configuration and the use of sheetmetal which has certain critical characteristics. The sheet metal mustbe that which has a Rockwell hardness (scale T-30) of about 54 to 72.Such sheet metal is commonly referred to as temper three, 54 to 62,temper four, 60 to 64, or Universal temper metal, 64 to 68. If the sheetmetal used does not meet this limitation such as with a softer metal,for example, temper one or temper two sheet metal, the sound which mayresult will be barely audible which is, of course, undesirable. Inaddition if the central domed part does not exhibit a curved surface incross-section but instead at least in part is a flat surface, the lightdirecting properties aforementioned will not be obtained. Also, the samewill have an adverse effect on the sound producing properties of thecap. For instance a cap produced according to this invention producestwice as much sound as caps which do not have the required upwardlydomed central part or are formed from less hard metal such as temper onesheet metal. In addition the frequency of the sound produced by this capis in the range of 400 to 4000 cycles which is the range where the earis most sensitive.

It should be apparent from the foregoing that we have discovered that byforming a closure cap of certain specified configuration from sheetmetal of certain properties, we are able to obtain a closure cap havingimportant characteristics not heretofore attainable. This closure capnot only provides an effective seal but more importantly provides one bywhich the presence or absence of the desired vacuum is easilydetermined. It also provides a very loud click upon the release of thevacuum.

The sheet metal commonly used for these caps is 75, and pound tinplate.However other sheet metals, such as steel that has not been tinplated,may be used equally as well.

Various modifications will be apparent from a reading of the foregoingdescription and as such are intended to be within the spirit and scopeof this invention.

We claim:

1. A sheet metal closure cap for hermetically vacuum sealing a glasscontainer comprising a disc-like panel portion, a depending attachingskirt at the periphery of the panel portion, said panel portion havingan annular substantially fiat area in proximity to its periphery, and asubstantially parabolic shaped and normally upwardly domed axiallyresilient central part peripherally defined by the substantially flatarea, and a sealing gasket carried by the closure cap, said sheet metalhaving a Rockwell hardness of about 54 to 72.

2. A sheet metal closure cap for hermetically vacuum sealing a glasscontainer comprising a disc-like panel portion, a depending attachingskirt at the periphery of the panel portion, said panel portion havingan annular substantially fiat area in proximity to its periphery and asubstantially parabolic shaped and normally upwardly domed axiallyresilient central part peripherally defined by the substantially fiatarea, said parabolic shaped domed part having a radius at its highestpoint of about 5 to 10 inches, and a sealing gasket carried by theclosure cap, said sheet metal having a Rockwell hardness of about 64 to68.

3. A sheet metal closure cap according to claim 2 wherein said radius isabout 7.0 inches.

4. A sheet. metal closure cap according to claim 2 wherein saidparabolic shaped domed part has a radius at its periphery of about /2 to1.0 inch.

5. A sheet metal closure cap according to claim 4 wherein said radius atthe periphery of said domed part is about .7 of an inch.

References Cited in the file of this patent UNITED STATES PATENTS1,805,623 Hammer May 19, 1931 2,027,430 Hansen Jan. 14, 1936 2,423,295Crabbe et al. July 1, 1947 2,449,014 Shatter Sept. 7, 1948 2,458,360 Fayet al. Jan. 4, 1949 2,953,272 Mumford et al Sept. 20, 1960

1. A SHEET METAL CLOSURE CAP FOR HERMETICALLY VACUUM SEALING A GLASSCONTAINER COMPRISING A DISC-LIKE PANEL PORTION, A DEPENDING ATTACHINGSKIRT AT THE PERIPHERY OF THE PANEL PORTION, SAID PANEL PORTION HAVINGAN ANNULAR SUBSTANTIALLY FLAT AREA IN PROXIMITY TO ITS PERIPHERY, AND ASUBSTANTIALLY PARABOLIC SHAPED AND NORMALLY UPWARDLY DOMED AXIALLYRESILIENT CENTRAL PART PERIPHERALLY DEFINED BY THE SUBSTANTIALLY FLATAREA, AND A SEALING GASKET CARRIED BY THE CLOSURE CAP, SAID SHEET METALHAVING A ROCKWELL HARDNESS OF ABOUT 54 TO 72.